COVID-19 among solid organ transplant recipients in Korea: surveillance data of the Korean Transplantation Society, January 2020 to March 2022.

Dear Editor:

Since the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in China in December 2019, the virus has spread worldwide, and the coronavirus disease 2019 (COVID-19) pandemic remains ongoing [1]. However, there are no published reports on the incidence rate and clinical outcomes of COVID-19 among Korean solid organ transplant (SOT) recipients, a high-risk group for severe COVID-19 [2,3]. Since January 2020, the Korean Transplantation Society has been collecting information on cases of SARS-CoV-2 infection in SOT recipients through members’ voluntary reports. According to the Korean government’s strategy, confirmed cases are defined as those with a positive result by real-time reverse-transcription polymerase chain reaction (RT-PCR) tests before March 14, 2022, and those with positive RT-PCR or rapid antigen test results after March 15, 2022. In South Korea, the first patient infected with the Omicron variant was identified on November 24, 2021, after which the Omicron variant spread rapidly and became predominant. We summarize the descriptive data collected. A total of 628 confirmed COVID-19 cases in SOT recipients were reported between January 2020 and March 2022. The demographic and clinical characteristics of the 628 patients are shown in Table 1. The majority of SOT recipients (58.4%) were male, and the median age at the time of infection was 57.0 years (interquartile range, 45.0–64.0 years). Kidney transplantation (79.3%) was the most common organ transplantation type, followed by liver transplantation (16.7%), heart transplantation (2.1%), lung transplantation (1.8%), and pancreas transplantation (0.2%). During the 24-month period from January 2020 to December 2021, 11.5 cases per month were reported, whereas 117.7 cases per month were reported during the 3 months from January 2022 to March 2022 (as of January 2022, when the Omicron variant became predominant in Korea) (Fig. 1). During the same period, the total number of confirmed cases in the Korean population was 635,253 (26,468.9 cases per month) until December 2021 and 12,740,565 (4,246,855 cases per month) from January to March 2022.

Table 1

Characteristics of solid organ transplant recipients with COVID-19

Characteristic	Case (n=628)
Sex
Male	364 (58.0)
Female	259 (41.2)
Unknown	5 (0.8)
Age (yr)
<20	24 (3.8)
20–49	174 (27.7)
50–59	169 (26.9)
60–69	200 (31.8)
≥70	61 (9.7)
Organ transplantation type
Kidney	498 (79.3)
Liver	105 (16.7)
Heart[a)]	13 (2.1)
Lung	11 (1.8)
Pancreas	1 (0.2)
Site of isolation and treatment
Hospital	309 (49.2)
Community health center	7 (1.1)
Self-quarantine	271 (43.2)
Unknown	41 (6.5)
Clinical course
Full recovery and release from quarantine	438 (69.7)
Ongoing treatment/follow-up information required	99 (15.8)
Death	13 (2.1)
Unknown	78 (12.4)

Values are presented as number (%).

COVID-19, coronavirus disease 2019.

a)In one case, simultaneous heart and kidney transplantation was performed.

Fig. 1

The monthly number of coronavirus disease 2019 (COVID-19) cases in solid organ transplant (SOT) recipients in Korea, (A) by SOT type, (B) by sex, (C) by age, (D) by site of isolation and treatment, and (E) by clinical course.

In the period until December 2021, 85.5% (235/275) of cases were hospitalized, whereas from January to March 2022, self-quarantine was the most common site of isolation and treatment (71.7%, 253/353). Eleven cases (2.1%) were reported to be fatal, corresponding to a higher mortality rate than among members of the general population diagnosed with COVID-19 in Korea aged 50–59 years (0.04%) and 70–79 years (0.68%) [4].

This study is the first to report the epidemiology and clinical outcomes of COVID-19 in Korean SOT recipients. However, voluntary reporting-based surveillance data may be underreported, particularly in the context of a rapidly spreading epidemic [5]. Despite the limitations of the data collected, we observed higher mortality in SOT recipients with COVID-19. Further studies are needed to accurately evaluate the epidemiology and risk of severe infection in SOT recipients in Korea.